Propellent powder



PROPELLENT POWDER Don W. Ryker, Alton, Ill., and Gilbert R. Cox, Creve Coeur, Mo., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia No Drawing. Filed June 14, 1951, Ser. No. 231,648

18 Claims. (Cl. 52-6) This invention relates to propellent powders and more particularly to a process of manufacturing substantially spherical grains of smokeless powder.

Spherical grains of powder have been made, heretofore, in accordance with the process disclosed by Olsen, Tibbitts and Kerone in U.S. Patent 2,027,114. In this process,.globules of lacquer comprising a smokeless powder base and a solvent are dispersed in a non-solvent medium and the globules solidified while thus dispersed. This process of making powder grains has proven eminently successful particularly when ethyl acetate is used as the smokeless powder base solvent and water as the dispersing medium. For some purposes, it is desirable to include lead compounds in powder grains, as for example to control burning rate, other ballistic properties, and the like. It has been found that when ethyl acetate is utilized as the solvent and water as the dispersing medium that an appreciable percentage of the lead compound added is not retained in the solidified powder grains. It is believed that some of the ethyl acetate is hydrolyzed to form acetic acid which reacts with lead compounds to form lead acetate which is soluble in the water phase and either remains therein as a solute or is precipitated therefrom as the result of reaction with other chemicals present, such as salts or protein type colloids.

It is therefore an object of this invention to provide an improvement whereby lead compounds can be incorporated in spherical grains of powder. It is a further object of this invention to provide a method of incorporating controlled amounts of lead compounds in spherical powder grains. Another object is to provide a process in which lead compounds are uniformly dispersed throughout the powder grain. A still further object of this invention is to provide a spherical powder grain having modified burning characteristics. A more specific object is to provide a powder grain containing lead soaps.

The foregoing objects as well as others which will become apparent from the following description are accomplished in accordance with this invention, generally stated, by suspending globules of lacquer containing a smokeless powder base, methyl ethyl ketone, a non-solvent diluent and lead in an aqueous medium and solidifying the globules while dispersed; said. lead having been mixed with the methyl ethyl ketone and non-solvent diluent prior to mixing with the aqueous medium. Some lead compounds, for instance lead soaps are soluble to some extent in the admixture of methyl ethyl ketone and non-solvent diluent, particularly toluene (said admixture hereinafter referred to variously as vehicle or lacquer vehicle), the solubility increasing with increase in temperature. Lead compounds which are totally insoluble or in amounts which exceed the solubility thereof in the vehicle can be utilized, the uniformity of dispersion of the lead compound in the solidified powder grain varying with the uniformity of the dispersion of insoluble lead compound in the vehicle and lacquer globules. It is therefore preferable, particularly when amounts of a lead compound which exceed the solubility thereof in the vehicle are to be utilized, to uniformly disperse the lead compound throughout the vehicle, although in some cases satisfactory powder grains can be produced when the lead compound and vehicle have been merely added one to the other.

The composition of the lacquer vehicle to be utilized will vary with the amount of lead compound desired in the solidified powder grains and also with other ingre dients to be included in the powder grains. For instance, deterrents and plasticizers such as dioctylphth-alate, dibutylphthalate, dinitrotoluene and the like, stabilizers, for example diphenylamine and Z-nitrodiphenylamine and the like, carbon black and other pulverulent insoluble modifiers and nitroglycerine can be incorporated in the powder grains and may be introduced as an ingredient of the lacquer vehicle composition. The desired density of the powder grains is also to be considered when formulating the lacquer vehicle as the porosity of the powder grain can be regulated to some extent by variation of the non-solvent diluent concentration in the vehicle. As disclosed by Cox in his co-pending application, Serial No. 231,647, filed of even date, now Patent No. 2,715,574, issued August 16, 1955, the porosity of spherical powder grains can be regulated by varying the concentration of non-solvent diluent in a lacquer vehicle containing a smokeless powder base solvent which is at least partially miscible with the non-solvent medium in which the lacquer globules are suspended. It has been found, however, that when lead soaps are incorporated in powder grains that a lacquer vehicle comprising methyl ethyl ketone must contain at least about 20% non-solvent diluent to be utilized to produce high density powder. Ordinarily, amounts of non-solvent diluent of as much as 20% are satisfactory for the purpose, particularly when toluene is utilized, although amounts up to have been utilized successfully with a smokeless powder base having a nitrogen content of about 12.6%. When a vehicle containing methyl ethyl ketone and less than about 20% nonsolvent diluent is utilized, the powder grains have a gravimetric density of less than 0.900 gram per cubic centimeter and are normally considered to be low density powder grains. Powder grains having a gravimetric density of 0.900 or more can be made with a non-solvent diluent concentration of 5% or more in the methyl ethyl ketone when lead compounds other than lead soaps are incorporated in the grains.

In most instances a ratio of about 2.5 to 6 parts vehicle to 1 part smokeless powder base forms a lacquer having the proper physical properties. Differentiation of the aqueous medium without the lacquer globules from that within the globules can be accomplished in accordance with the disclosure of Schaefer in U.S. Patent 2,160,626 and protective colloid may be added to the aqueous medium in accordance with the disclosure in U.S. Patent 2,027,114.

For the purposes of this invention, the lead may be in the form of metallic lead as well as the chemical compounds of lead such as lead soaps, lead chromate, lead oxides, lead sulfide, lead carbonate and the like and in amounts varying from as little as a fraction of a percent up to large amounts. Amounts of lead compounds of about 0.5% to 10% based on the weight of the solidified powder grains are preferred. Examples of lead soaps which can be incorporated in spherical powder grains in accordance with this invention include lead stearate, lead oleate, lead palmitate, lead linoleate and the like. Nonsolvents substantially miscible with methyl ethyl ketone and substantially immiscible with water such as xylene,

benzene, pentane, hexane, heptane, octane, nonane,.

decane, undecane, dodecane, isopropyl ether, propyl ether, cyclohexane, methylcyclohexane or the like can be utilized In order to further explain and clarify this invention following are typical embodiments thereof.

Approximately 65 parts by weight smokeless powder base of'about 12.6% nitrogen contentfare suspended in about 900 parts water. About 7 parts lead stearate, 100 parts lacquer vehicle containing about 80% methyl ethyl ketone saturated with water and about 20% toluene, about 3.6 parts dioctylphthalate and about 1.4 parts 2- nitrodiphenylarnine are homogenized and diluted with about 260 parts vehicle having the same composition as that utilized for the foregoing dispersion medium. This mixture is then added to the aqueous slurry of smokeless powder base and agitated until substantially complete solution of the smokeless powder base. About 35 parts animal glue dissolved in about 80 parts water are added to the slurry and agitation continued until the lacquer is completely dispersed in the water phase and' the individual globules thus formed become substantially spherical. Approximately 35 parts sodium sulfate dissolved in about 100 parts water are added and the vehicle removed from the lacquer globules by distillation while in suspension in the water. The solidified grains are then dewatered by filtering and oven drying. Powder grains made in accordance with the foregoing procedure have been found to contain about 4.5% lead stearate uniformly dispersed throughout the grain and to have a gravimetric density of about 0.920.

In a second example, approximately 36 parts smokeless powder base of about 12.6% nitrogen content are suspended in about 350 parts water. About 3.6 parts lead stearate, 50 parts lacquer vehicle containing about 95% methyl ethyl ketone saturated with water and about toluene, approximately 2.0 parts dioctylphthalate and about .8 part Z-nitrodiphenylamine are homogenized and this mixture diluted with about 140 parts lacquer vehicle of the same composition as that utilized in making the foregoing dispersion. This mixture is then added to the aqueous slurry of smokeless powder base and agitated until the smokeless powder base has dissolved.'

About 5 parts gum arabic in 30 parts water are added to the slurry and agitation continued until the lacquer is completely dispersed in the water phase and the individual globules thus formed become substantially spherical. Approximately 25 parts sodium sulfate dissolved in about 30 parts water are added and the vehicle removed from the lacquer globules by distillation While suspended in the water. The solidified grains are then dewatered by filtering and oven drying. Powder grains made in accordance with the foregoing procedure have been found to contain about 5% lead stearate uniformly dispersed throughout and to have a gravimetric density of about 0.725.

From the foregoing description, it will be apparent to those skilled in the art that the invention accomplishes its objects and provides a spherical powder grain containing a lead compound uniformly dispersed throughout and provides a method of incorporating lead compounds in powder grains.

While the foregoing embodiments have been described in detail, it is to be distinctly understood that various modifications of the procedure will occur to those skilled in the art and that the invention is not limited to the specific embodiments hereinbefore set forth, except as indicated in the appended claims.

Having thus described the invention, what is claimed and desire to secure by' Letters Patent is:

1. In the manufacture of powder grains by a process which involves dispersing globules of lacquer containing a smokeless powder base and a vehicle in an aqueous medium and thereafter solidifying the globules while dispersed, the method of shaping and solidifying lacquer globules into gelatinized droplets of smokeless powder base having lead therein which comprises dissolving the smokeless powder base in a vehicle having lead incorporated therein and containing methyl ethyl ketone and a volatile liquid non-solvent which is substantially miscible with methyl ethyl ketone and reduces the miscibility of water therewith, and thereafter solidifying the globules while suspended in the aqueous medium.

2. The process of claim 1 wherein said lead is in the form of lead .chromate. I

3. The process of claim 1 wherein said lead is in the form of a lead soap.

4. The process of claim 1 wherein said non-solvent diluent is toluene and said lead is in the form of a lead soap.

5. The process set forth in claim 1 wherein said nonsolvent diluent is at least about 20% toluene.

6. The process of claim 3 wherein said lead soap is lead stearate.

7. In the manufactureof spherical powder. grains,..the.

process which comprises uniformly dispersing lead in a mixture of methyl ethyl ketone and a liquid non-solvent diluent, adding the mixture to an agitated aqueous medium containing a smokeless powder base suspended therein, adding a protective colloid and solidfying the resulting globules of smokeless powder base lacquer by vaporizing said methyl ethyl ketone and non-solvent diluent during agitation.

8. A powder grain composed essentially of a solidified droplet of gelatinized smokeless powder base and having lead dispersed therein.

9. The product of claim 8 wherein said lead is in the form of a lead soap.

10. The product of claim 8 wherein said lead is .uniformly dispersed throughout said powder grain.

11. The product of claim 10 wherein said lead is in the form of a lead soap.

12. A spherical powder grain composed essentially of a solidified droplet of gelatinized smokeless powder base and having a gravimetric density of at least about .900 containing lead substantially uniformly dispersed throughout.

13. The product of claim 12 wherein said lead is in the form of a lead soap.

14. In the manufacture of powder grains by a process which involves dispersing globules of a smokeless powder base lacquer in an aqueous medium, the step which comprises including in said lacquer lead and a non-solvent diluent.

15. In the manufacture of spherical powder grains, the process which comprises substantially uniformly dispersing a material selected from the group consisting of metallic lead, lead salts, and lead oxides in a mixture of methyl ethyl ketone and a non-solvent diluent, adding said dispersion to an agitated aqueous medium containing a smokeless powder base suspended therein, adding a protective colloid and solidifying the resulting globules of smokeless powder base lacquer while dispersed in the aqueous medium.

16. A substantially spherical smokeless powder base grain having a material dispersed therein selected from the group consisting of metallic lead, lead salts, and lead oxides.

17. In the manufacturing of powder grains wherein globules of lacquer containing a smokeless powder base and a vehicle are dispersed in an aqueous medium and solidified while dispersed, the process for making grains of low porosity containing lead which comprises dispersing lead in a mixture of methyl ethyl ketone and a nonsolvent diluent, dissolving a smokeless powder base in the dispersion, suspending globules of the resulting lacquer in anon-solvent medium and solidifying the globules while thus dispersed.

18. In the manufacture of powder grains by a process which involves suspending globules of lacquer containing a smokeless powder base and a vehicle in an aqueous medium and thereafter solidifying the globules while thus suspended, the method of shaping and solidifying a smokeless powder base lacquer into gelatinized droplets of smokeless powder base of predetermined porosity and having dispersed substantially uniformly therein a ballistic modifier selected from the group consisting of metallic lead, lead salts and lead oxides, which comprises dissolving the smokeless powder base in a vehicle having in its composition a ballistic modifier of the class specified dispersed in methyl ethyl ketone and a volatile liquid nonsolvent for the smokeless powder base which is substantially miscible with methyl ethyl ketone and which reduces the miscibility of water with the resulting lacquer, and thereafter solidifying globules of the lacquer While they are suspended in an aqueous medium containing a protective colloid.

References Cited in the file of this patent UNITED STATES PATENTS Adinau Mar. 13, 1913 Henning Nov. 2, 1920 Hawkins Nov. 22, 1921 Spurlin July 17, 1934 Olsen et al Jan. 7, 1936 Schaefer May 30, 1939 Olsen et al. Sept. 3, 1940 Olsen Aug. 11, 1942 Herzog Feb. 5, 1946 Ball Feb. 21, 1950 

1. IN THE MANUFACTURE OF POWDER GRAINS BY A PROCESS WHICH INVOLVES DISPERSING GLOBULES OF LACQUER CONTAINING A SMOKELESS POWDER BASE AND A VEHICLE IN AN AQUEOUS MEDIUM AND THEREAFTER SOLIDIFYING THE GLOBULES WHILE DISPERSED, THE METHOD OF SHAPING AND SOLIDIFYING LACQUER GLOBULES INTO GELATINIZED DROPLETS OF SMOKELESS POWDER BASE HAVING LEAD THEREIN WHICH COMPRISES DISSOLVING THE SMOKELESS POWDER BASE IN A VEHICLE HAVING LEAD INCORPORATED THEREIN AND CONTAINING METHYL ETHYL KETONE AND A VOLATILE LIQUID NON-SOLVENT WHICH IS SUBSTANTIALLY MISCIBLE WITH METHYL ETHYL KETONE AND REDUCES THE MISCIBILITY OF WATER THEREWITH, AND THEREAFTER SOLIDIFYING THE GLOBULES WHILE SUSPENDED IN THE AQUEOUS MEDIUM.
 16. A SUBSTANTIALLY SPHERICAL SMOKELESS POWDER BASE GRAIN HAVING A MATERIAL DISPERSED THEREIN SELECTED FROM THE GROUP CONSISTING OF METALLIC LEAD, LEAD SALTS, AND LEAD OXIDES. 